xref: /qemu/include/qemu/bitops.h (revision a18025f9) 
1 /*
2  * Bitops Module
3  *
4  * Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
5  *
6  * Mostly inspired by (stolen from) linux/bitmap.h and linux/bitops.h
7  *
8  * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
9  * See the COPYING.LIB file in the top-level directory.
10  */
11 
12 #ifndef BITOPS_H
13 #define BITOPS_H
14 
15 
16 #include "host-utils.h"
17 #include "atomic.h"
18 
19 #define BITS_PER_BYTE           CHAR_BIT
20 #define BITS_PER_LONG           (sizeof (unsigned long) * BITS_PER_BYTE)
21 
22 #define BIT(nr)                 (1UL << (nr))
23 #define BIT_ULL(nr)             (1ULL << (nr))
24 #define BIT_MASK(nr)            (1UL << ((nr) % BITS_PER_LONG))
25 #define BIT_WORD(nr)            ((nr) / BITS_PER_LONG)
26 #define BITS_TO_LONGS(nr)       DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
27 
28 #define MAKE_64BIT_MASK(shift, length) \
29     (((~0ULL) >> (64 - (length))) << (shift))
30 
31 /**
32  * set_bit - Set a bit in memory
33  * @nr: the bit to set
34  * @addr: the address to start counting from
35  */
36 static inline void set_bit(long nr, unsigned long *addr)
37 {
38     unsigned long mask = BIT_MASK(nr);
39     unsigned long *p = addr + BIT_WORD(nr);
40 
41     *p  |= mask;
42 }
43 
44 /**
45  * set_bit_atomic - Set a bit in memory atomically
46  * @nr: the bit to set
47  * @addr: the address to start counting from
48  */
49 static inline void set_bit_atomic(long nr, unsigned long *addr)
50 {
51     unsigned long mask = BIT_MASK(nr);
52     unsigned long *p = addr + BIT_WORD(nr);
53 
54     atomic_or(p, mask);
55 }
56 
57 /**
58  * clear_bit - Clears a bit in memory
59  * @nr: Bit to clear
60  * @addr: Address to start counting from
61  */
62 static inline void clear_bit(long nr, unsigned long *addr)
63 {
64     unsigned long mask = BIT_MASK(nr);
65     unsigned long *p = addr + BIT_WORD(nr);
66 
67     *p &= ~mask;
68 }
69 
70 /**
71  * change_bit - Toggle a bit in memory
72  * @nr: Bit to change
73  * @addr: Address to start counting from
74  */
75 static inline void change_bit(long nr, unsigned long *addr)
76 {
77     unsigned long mask = BIT_MASK(nr);
78     unsigned long *p = addr + BIT_WORD(nr);
79 
80     *p ^= mask;
81 }
82 
83 /**
84  * test_and_set_bit - Set a bit and return its old value
85  * @nr: Bit to set
86  * @addr: Address to count from
87  */
88 static inline int test_and_set_bit(long nr, unsigned long *addr)
89 {
90     unsigned long mask = BIT_MASK(nr);
91     unsigned long *p = addr + BIT_WORD(nr);
92     unsigned long old = *p;
93 
94     *p = old | mask;
95     return (old & mask) != 0;
96 }
97 
98 /**
99  * test_and_clear_bit - Clear a bit and return its old value
100  * @nr: Bit to clear
101  * @addr: Address to count from
102  */
103 static inline int test_and_clear_bit(long nr, unsigned long *addr)
104 {
105     unsigned long mask = BIT_MASK(nr);
106     unsigned long *p = addr + BIT_WORD(nr);
107     unsigned long old = *p;
108 
109     *p = old & ~mask;
110     return (old & mask) != 0;
111 }
112 
113 /**
114  * test_and_change_bit - Change a bit and return its old value
115  * @nr: Bit to change
116  * @addr: Address to count from
117  */
118 static inline int test_and_change_bit(long nr, unsigned long *addr)
119 {
120     unsigned long mask = BIT_MASK(nr);
121     unsigned long *p = addr + BIT_WORD(nr);
122     unsigned long old = *p;
123 
124     *p = old ^ mask;
125     return (old & mask) != 0;
126 }
127 
128 /**
129  * test_bit - Determine whether a bit is set
130  * @nr: bit number to test
131  * @addr: Address to start counting from
132  */
133 static inline int test_bit(long nr, const unsigned long *addr)
134 {
135     return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
136 }
137 
138 /**
139  * find_last_bit - find the last set bit in a memory region
140  * @addr: The address to start the search at
141  * @size: The maximum size to search
142  *
143  * Returns the bit number of the first set bit, or size.
144  */
145 unsigned long find_last_bit(const unsigned long *addr,
146                             unsigned long size);
147 
148 /**
149  * find_next_bit - find the next set bit in a memory region
150  * @addr: The address to base the search on
151  * @offset: The bitnumber to start searching at
152  * @size: The bitmap size in bits
153  */
154 unsigned long find_next_bit(const unsigned long *addr,
155                             unsigned long size,
156                             unsigned long offset);
157 
158 /**
159  * find_next_zero_bit - find the next cleared bit in a memory region
160  * @addr: The address to base the search on
161  * @offset: The bitnumber to start searching at
162  * @size: The bitmap size in bits
163  */
164 
165 unsigned long find_next_zero_bit(const unsigned long *addr,
166                                  unsigned long size,
167                                  unsigned long offset);
168 
169 /**
170  * find_first_bit - find the first set bit in a memory region
171  * @addr: The address to start the search at
172  * @size: The maximum size to search
173  *
174  * Returns the bit number of the first set bit.
175  */
176 static inline unsigned long find_first_bit(const unsigned long *addr,
177                                            unsigned long size)
178 {
179     unsigned long result, tmp;
180 
181     for (result = 0; result < size; result += BITS_PER_LONG) {
182         tmp = *addr++;
183         if (tmp) {
184             result += ctzl(tmp);
185             return result < size ? result : size;
186         }
187     }
188     /* Not found */
189     return size;
190 }
191 
192 /**
193  * find_first_zero_bit - find the first cleared bit in a memory region
194  * @addr: The address to start the search at
195  * @size: The maximum size to search
196  *
197  * Returns the bit number of the first cleared bit.
198  */
199 static inline unsigned long find_first_zero_bit(const unsigned long *addr,
200                                                 unsigned long size)
201 {
202     return find_next_zero_bit(addr, size, 0);
203 }
204 
205 /**
206  * rol8 - rotate an 8-bit value left
207  * @word: value to rotate
208  * @shift: bits to roll
209  */
210 static inline uint8_t rol8(uint8_t word, unsigned int shift)
211 {
212     return (word << shift) | (word >> ((8 - shift) & 7));
213 }
214 
215 /**
216  * ror8 - rotate an 8-bit value right
217  * @word: value to rotate
218  * @shift: bits to roll
219  */
220 static inline uint8_t ror8(uint8_t word, unsigned int shift)
221 {
222     return (word >> shift) | (word << ((8 - shift) & 7));
223 }
224 
225 /**
226  * rol16 - rotate a 16-bit value left
227  * @word: value to rotate
228  * @shift: bits to roll
229  */
230 static inline uint16_t rol16(uint16_t word, unsigned int shift)
231 {
232     return (word << shift) | (word >> ((16 - shift) & 15));
233 }
234 
235 /**
236  * ror16 - rotate a 16-bit value right
237  * @word: value to rotate
238  * @shift: bits to roll
239  */
240 static inline uint16_t ror16(uint16_t word, unsigned int shift)
241 {
242     return (word >> shift) | (word << ((16 - shift) & 15));
243 }
244 
245 /**
246  * rol32 - rotate a 32-bit value left
247  * @word: value to rotate
248  * @shift: bits to roll
249  */
250 static inline uint32_t rol32(uint32_t word, unsigned int shift)
251 {
252     return (word << shift) | (word >> ((32 - shift) & 31));
253 }
254 
255 /**
256  * ror32 - rotate a 32-bit value right
257  * @word: value to rotate
258  * @shift: bits to roll
259  */
260 static inline uint32_t ror32(uint32_t word, unsigned int shift)
261 {
262     return (word >> shift) | (word << ((32 - shift) & 31));
263 }
264 
265 /**
266  * rol64 - rotate a 64-bit value left
267  * @word: value to rotate
268  * @shift: bits to roll
269  */
270 static inline uint64_t rol64(uint64_t word, unsigned int shift)
271 {
272     return (word << shift) | (word >> ((64 - shift) & 63));
273 }
274 
275 /**
276  * ror64 - rotate a 64-bit value right
277  * @word: value to rotate
278  * @shift: bits to roll
279  */
280 static inline uint64_t ror64(uint64_t word, unsigned int shift)
281 {
282     return (word >> shift) | (word << ((64 - shift) & 63));
283 }
284 
285 /**
286  * extract32:
287  * @value: the value to extract the bit field from
288  * @start: the lowest bit in the bit field (numbered from 0)
289  * @length: the length of the bit field
290  *
291  * Extract from the 32 bit input @value the bit field specified by the
292  * @start and @length parameters, and return it. The bit field must
293  * lie entirely within the 32 bit word. It is valid to request that
294  * all 32 bits are returned (ie @length 32 and @start 0).
295  *
296  * Returns: the value of the bit field extracted from the input value.
297  */
298 static inline uint32_t extract32(uint32_t value, int start, int length)
299 {
300     assert(start >= 0 && length > 0 && length <= 32 - start);
301     return (value >> start) & (~0U >> (32 - length));
302 }
303 
304 /**
305  * extract64:
306  * @value: the value to extract the bit field from
307  * @start: the lowest bit in the bit field (numbered from 0)
308  * @length: the length of the bit field
309  *
310  * Extract from the 64 bit input @value the bit field specified by the
311  * @start and @length parameters, and return it. The bit field must
312  * lie entirely within the 64 bit word. It is valid to request that
313  * all 64 bits are returned (ie @length 64 and @start 0).
314  *
315  * Returns: the value of the bit field extracted from the input value.
316  */
317 static inline uint64_t extract64(uint64_t value, int start, int length)
318 {
319     assert(start >= 0 && length > 0 && length <= 64 - start);
320     return (value >> start) & (~0ULL >> (64 - length));
321 }
322 
323 /**
324  * sextract32:
325  * @value: the value to extract the bit field from
326  * @start: the lowest bit in the bit field (numbered from 0)
327  * @length: the length of the bit field
328  *
329  * Extract from the 32 bit input @value the bit field specified by the
330  * @start and @length parameters, and return it, sign extended to
331  * an int32_t (ie with the most significant bit of the field propagated
332  * to all the upper bits of the return value). The bit field must lie
333  * entirely within the 32 bit word. It is valid to request that
334  * all 32 bits are returned (ie @length 32 and @start 0).
335  *
336  * Returns: the sign extended value of the bit field extracted from the
337  * input value.
338  */
339 static inline int32_t sextract32(uint32_t value, int start, int length)
340 {
341     assert(start >= 0 && length > 0 && length <= 32 - start);
342     /* Note that this implementation relies on right shift of signed
343      * integers being an arithmetic shift.
344      */
345     return ((int32_t)(value << (32 - length - start))) >> (32 - length);
346 }
347 
348 /**
349  * sextract64:
350  * @value: the value to extract the bit field from
351  * @start: the lowest bit in the bit field (numbered from 0)
352  * @length: the length of the bit field
353  *
354  * Extract from the 64 bit input @value the bit field specified by the
355  * @start and @length parameters, and return it, sign extended to
356  * an int64_t (ie with the most significant bit of the field propagated
357  * to all the upper bits of the return value). The bit field must lie
358  * entirely within the 64 bit word. It is valid to request that
359  * all 64 bits are returned (ie @length 64 and @start 0).
360  *
361  * Returns: the sign extended value of the bit field extracted from the
362  * input value.
363  */
364 static inline int64_t sextract64(uint64_t value, int start, int length)
365 {
366     assert(start >= 0 && length > 0 && length <= 64 - start);
367     /* Note that this implementation relies on right shift of signed
368      * integers being an arithmetic shift.
369      */
370     return ((int64_t)(value << (64 - length - start))) >> (64 - length);
371 }
372 
373 /**
374  * deposit32:
375  * @value: initial value to insert bit field into
376  * @start: the lowest bit in the bit field (numbered from 0)
377  * @length: the length of the bit field
378  * @fieldval: the value to insert into the bit field
379  *
380  * Deposit @fieldval into the 32 bit @value at the bit field specified
381  * by the @start and @length parameters, and return the modified
382  * @value. Bits of @value outside the bit field are not modified.
383  * Bits of @fieldval above the least significant @length bits are
384  * ignored. The bit field must lie entirely within the 32 bit word.
385  * It is valid to request that all 32 bits are modified (ie @length
386  * 32 and @start 0).
387  *
388  * Returns: the modified @value.
389  */
390 static inline uint32_t deposit32(uint32_t value, int start, int length,
391                                  uint32_t fieldval)
392 {
393     uint32_t mask;
394     assert(start >= 0 && length > 0 && length <= 32 - start);
395     mask = (~0U >> (32 - length)) << start;
396     return (value & ~mask) | ((fieldval << start) & mask);
397 }
398 
399 /**
400  * deposit64:
401  * @value: initial value to insert bit field into
402  * @start: the lowest bit in the bit field (numbered from 0)
403  * @length: the length of the bit field
404  * @fieldval: the value to insert into the bit field
405  *
406  * Deposit @fieldval into the 64 bit @value at the bit field specified
407  * by the @start and @length parameters, and return the modified
408  * @value. Bits of @value outside the bit field are not modified.
409  * Bits of @fieldval above the least significant @length bits are
410  * ignored. The bit field must lie entirely within the 64 bit word.
411  * It is valid to request that all 64 bits are modified (ie @length
412  * 64 and @start 0).
413  *
414  * Returns: the modified @value.
415  */
416 static inline uint64_t deposit64(uint64_t value, int start, int length,
417                                  uint64_t fieldval)
418 {
419     uint64_t mask;
420     assert(start >= 0 && length > 0 && length <= 64 - start);
421     mask = (~0ULL >> (64 - length)) << start;
422     return (value & ~mask) | ((fieldval << start) & mask);
423 }
424 
425 /**
426  * half_shuffle32:
427  * @value: 32-bit value (of which only the bottom 16 bits are of interest)
428  *
429  * Given an input value:
430  *  xxxx xxxx xxxx xxxx ABCD EFGH IJKL MNOP
431  * return the value where the bottom 16 bits are spread out into
432  * the odd bits in the word, and the even bits are zeroed:
433  *  0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N 0O0P
434  *
435  * Any bits set in the top half of the input are ignored.
436  *
437  * Returns: the shuffled bits.
438  */
439 static inline uint32_t half_shuffle32(uint32_t x)
440 {
441     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
442      * It ignores any bits set in the top half of the input.
443      */
444     x = ((x & 0xFF00) << 8) | (x & 0x00FF);
445     x = ((x << 4) | x) & 0x0F0F0F0F;
446     x = ((x << 2) | x) & 0x33333333;
447     x = ((x << 1) | x) & 0x55555555;
448     return x;
449 }
450 
451 /**
452  * half_shuffle64:
453  * @value: 64-bit value (of which only the bottom 32 bits are of interest)
454  *
455  * Given an input value:
456  *  xxxx xxxx xxxx .... xxxx xxxx ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
457  * return the value where the bottom 32 bits are spread out into
458  * the odd bits in the word, and the even bits are zeroed:
459  *  0A0B 0C0D 0E0F 0G0H 0I0J 0K0L 0M0N .... 0U0V 0W0X 0Y0Z 0a0b 0c0d 0e0f
460  *
461  * Any bits set in the top half of the input are ignored.
462  *
463  * Returns: the shuffled bits.
464  */
465 static inline uint64_t half_shuffle64(uint64_t x)
466 {
467     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
468      * It ignores any bits set in the top half of the input.
469      */
470     x = ((x & 0xFFFF0000ULL) << 16) | (x & 0xFFFF);
471     x = ((x << 8) | x) & 0x00FF00FF00FF00FFULL;
472     x = ((x << 4) | x) & 0x0F0F0F0F0F0F0F0FULL;
473     x = ((x << 2) | x) & 0x3333333333333333ULL;
474     x = ((x << 1) | x) & 0x5555555555555555ULL;
475     return x;
476 }
477 
478 /**
479  * half_unshuffle32:
480  * @value: 32-bit value (of which only the odd bits are of interest)
481  *
482  * Given an input value:
483  *  xAxB xCxD xExF xGxH xIxJ xKxL xMxN xOxP
484  * return the value where all the odd bits are compressed down
485  * into the low half of the word, and the high half is zeroed:
486  *  0000 0000 0000 0000 ABCD EFGH IJKL MNOP
487  *
488  * Any even bits set in the input are ignored.
489  *
490  * Returns: the unshuffled bits.
491  */
492 static inline uint32_t half_unshuffle32(uint32_t x)
493 {
494     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
495      * where it is called an inverse half shuffle.
496      */
497     x &= 0x55555555;
498     x = ((x >> 1) | x) & 0x33333333;
499     x = ((x >> 2) | x) & 0x0F0F0F0F;
500     x = ((x >> 4) | x) & 0x00FF00FF;
501     x = ((x >> 8) | x) & 0x0000FFFF;
502     return x;
503 }
504 
505 /**
506  * half_unshuffle64:
507  * @value: 64-bit value (of which only the odd bits are of interest)
508  *
509  * Given an input value:
510  *  xAxB xCxD xExF xGxH xIxJ xKxL xMxN .... xUxV xWxX xYxZ xaxb xcxd xexf
511  * return the value where all the odd bits are compressed down
512  * into the low half of the word, and the high half is zeroed:
513  *  0000 0000 0000 .... 0000 0000 ABCD EFGH IJKL MNOP QRST UVWX YZab cdef
514  *
515  * Any even bits set in the input are ignored.
516  *
517  * Returns: the unshuffled bits.
518  */
519 static inline uint64_t half_unshuffle64(uint64_t x)
520 {
521     /* This algorithm is from _Hacker's Delight_ section 7-2 "Shuffling Bits".
522      * where it is called an inverse half shuffle.
523      */
524     x &= 0x5555555555555555ULL;
525     x = ((x >> 1) | x) & 0x3333333333333333ULL;
526     x = ((x >> 2) | x) & 0x0F0F0F0F0F0F0F0FULL;
527     x = ((x >> 4) | x) & 0x00FF00FF00FF00FFULL;
528     x = ((x >> 8) | x) & 0x0000FFFF0000FFFFULL;
529     x = ((x >> 16) | x) & 0x00000000FFFFFFFFULL;
530     return x;
531 }
532 
533 #endif
534